Exploring the protective effects of calcium-containing carrier against drying-induced cellular injuries of probiotics using single droplet drying technique
Résumé
Protective carriers that encapsulate probiotics in spray drying could improve the survival ratio of dried cells
through different mechanisms. Unveiling the protective mechanism of each carrier will contribute to a rational
design of high performance carrier formulation. This study utilized single droplet drying (SDD) technique to investigate the effects of calcium cation in varied carrier formulation. Inactivation histories of Lactobacillus
rhamnosus GG (LGG) in different carriers were compared, and cellular injury history of probiotics during droplet
drying was studied for the first time. Adding 1 mMCaCl2 to lactose carrier protected cell viability, mitigated cellular injuries, and enhanced regrowth capability as drying progressed, demonstrating the positive effect of Ca2+ with possible mechanism of stabilizing sub-cellular structures. At later drying stages, cell survival in Lac/Ca carrierwas increased by 0.5–1.5 log on selective media compared to lactose carrier. Supplementing calcium-binding agents lowered the protective effect, shortening the initiation of rapid cell inactivation down to 120 s of drying. Adding CaCl2 to trehalose carrier barely improved cell survival, indicating that the protective effect could be influenced by carrier formulation. Pure trehalose carrier exerted excellent protection on LGG, supporting cells to regrow in liquid rich mediumeven after 180 s of drying. The protection of trehalose may stem from stabilization of sub-cellular structures, which possibly overlap the effect of Ca2+. The findings suggested that high performance
carrier formulation might be developed by combining carrier materials with different protective mechanisms,
for maximizing the survival of active dry probiotics in industrial spray drying operation.